Its 5 working days with all UK cheques paid to a bank. It may take longer if you pay a bank cheque in at a post office (This is down to it being posted to a bank).
The process itself takes 3 working days, the clearing still takes 5.
Day 1: Paid in to bank, at close of business, sent for clearing
Day 2, 3 and 4 (See link below) Clearing
Day 5: Sent back to bank, cleared
From the point you paid in, to the day you may safely draw the funds, it takes 5 working days.
Most banks will allow you to draw funds before the cheque is cleared, however if the cheque is returned, your account will be debited accordingly.
http://www.bba.org.uk/bba/jsp/polopoly.jsp?d=263&a=367
The above link shows the 3 day process, but ignores the fact that most if not all banks only collect cheques once per day.